Mark E. Orazem

Professor

Ph.D., 1983, University of California-Berkeley (1988)

Fuel Cells
Electrochemical impedance spectroscopy
Characterization of corrosion
Mathematical modeling

Email:	meo@che.ufl.edu
Phone:	(352) 392-6207
327 Chemical Engineering Building

Faculty Web Page - More Information

Brief Description of Current Research

A combined modeling and experimental program is intended to enhance the application of impedance spectroscopy as a tool for electrochemical characterization of polymer-electrolyte proton exchange membrane (PEM) fuel cells. The issues addressed include establishing the range of validity of data, establishing the relationship between electrode non-uniformity and overall impedance measurements, and developing interpretation models for the impedance response that based on the physics, transport, and kinetic mechanisms. The impedance models will integrate models for transport with multiple reactions associated with the fuel cell electrode assemblies. These models would therefore link the electrochemical processes with fluid flow and heat transfer. Experiments on one-dimensional systems will be used to extract kinetic parameters. Impedance spectroscopy may be sensitive to the side reactions that can result in degradation of the performance of the membrane electrode assembly.

The mathematical model for cathodic protection of buried structures CP3D developed by our group is being used to select and prioritize External Corrosion Direct Assessment (ECDA) procedures used to assess indications of poor pipeline integrity. This procedure, developed in collaboration with industry, will account for factors such as soil resistivity and coating defects that may lead to improper implementation of ECDA.

In collaboration with researchers in Metz and Paris, mathematical models are being developed to predict the rate of delamination of paint and coatings on steel and galvanized steel. The algorithm will take into account the barrier properties of the polymer layer, the galvanic couple between zinc and steel, the electrochemistry of the individual metal surfaces exposed, and the homogeneous (equilibrium) chemistry of solution species. An experimental program is being developed to test model results and assumptions.

In collaboration with NASA researchers, impedance techniques are being used to study the polymer electrolyte used in lithium-ion batteries. The objective of this work is to develop interpretation models that describe the impedance response in terms of physical and chemical properties.

A combined experimental and modeling investigation is being conducted in collaboration with researchers in Toulouse and Paris on the influence of electrode geometry on impedance response.

Major Equipment

Complete Electrochemical Laboratory (computer-interfaced instrumentation and metallographic preparation facilities)

Cell for In-Situ Ellipsometry (Gaertner)

Impedance Instrumentation (Solartron 1250/1286)

Center for Solid-State Measurements (including capabilities for Deep-Level Transient Spectroscopy (DLTS) and Optically- and Thermally-Stimulated Deep-Level Impedance Spectroscopy (0S-DLZS and TS-DLZS)).

Selected Publications

�A Mathematical Model for the Cathodic Protection of Tank Bottoms�, D.P. Riemer and M.E. Orazem, Corrosion Science, Vol. 47, 849-868 (2005).

�Modeling Coating Flaws with Non-Linear Polarization Curves for Long Pipelines�, D.P. Riemer and M.E. Orazem, Corrosion and Cathodic Protection Modeling and Simulation, Vol. Volume 12 of Advances in Boundary Elements, R.A. Adey, editor, WIT Press, Southampton, (to appear, 2005).

�Impedance Analysis for Reduction of Ferricyanide on a Submerged Hemispherical Ni270 Electrode�, P. Shukla, G. Nellisen, and M.E. Orazem, Electrochimica Acta, (to appear, 2005).

�CPE Analysis by Local Electrochemical Impedance Spectroscopy�, Electrochimica Acta, J.-B. Jorcin, M.E. Orazem, N. P�b�re, and B. Tribollet, (to appear, 2005).

�Application of Measurement Models to High Impedance Data of Steels in Used Oil�, K.N. Allahar, M.E. Orazem, D.P. Butt, H.A. Chin, and W. Ogden, Electrochimica Acta, (to appear, 2005).

�Validation of the Measurement Model Concept for Error Structure Identification�, P.K. Shukla, M.E. Orazem, and O.D. Crisalle, Electrochimica Acta, Vol. 49, 2881-2889 (2004).

�A Weighted Nonlinear Regression-Based Inverse Model for Interpretation of Pipeline Survey Data�, C. Qiu and M.E. Orazem, Electrochimica Acta, Vol. 49, 3965-3975 (2004).

�Assessment of Pipeline Condition Using Heterogeneous Input Data�, Journal of the Electrochemical Society, C. Qiu and M.E. Orazem, Vol. 151, B415-B422 (2004).